Intelligent clothing based on motion state driving to realize indoor and outdoor positioning switching

Abstract

The application discloses an intelligent garment based on motion state driving to realize indoor and outdoor positioning switching, and belongs to the technical field of intelligent wearing positioning. The existing positioning switching scheme only relies on GNSS signal strength determination, and is prone to mis-switching and positioning jumping in scenes such as urban canyons and window edges. The intelligent garment is provided with a main control unit, an IMU, a GNSS positioning module, an indoor positioning module and a power module on the garment body. The IMU is used to collect data to identify the motion states of a user in stillness, walking and running. In combination with the signal quality of the GNSS carrier-to-noise ratio, a double-condition hysteresis determination mechanism is adopted to realize indoor and outdoor positioning mode switching, and confirmation time with different lengths is matched to avoid switching jitter. Meanwhile, in the mode switching transition period, the IMU is used to realize the smooth connection of positioning data through dead reckoning. The application accurately matches the intention of the user entering and exiting the scene, effectively suppresses mis-switching, guarantees the continuity and stability of positioning, and can be widely applied to scenes such as the care of the elderly, the prevention of children from getting lost, outdoor rescue and the like.

Description

Technical Field

[0001] This invention relates to the field of smart wearable and positioning technology, and more specifically to a smart garment that achieves indoor and outdoor positioning switching based on motion state driving. Background Technology

[0002] With the development of smart wearable technology, smart clothing with positioning capabilities is widely used in scenarios such as elderly care, preventing children from getting lost, outdoor sports, and fire rescue. Outdoor positioning typically uses GNSS (Global Navigation Satellite System, such as GPS and BeiDou), which has high accuracy in open environments, but indoors the signal is attenuated or even fails due to building obstruction. Indoor positioning typically uses UWB (Ultra-Wideband), BLE (Bluetooth Low Energy), or WiFi, which have insufficient coverage and deployment density outdoors. Therefore, smart clothing needs to switch between outdoor GNSS positioning and indoor positioning.

[0003] Most existing indoor / outdoor positioning switching solutions rely solely on GNSS signal strength or signal-to-noise ratio (SNR): switching to indoor positioning when the SNR falls below a certain threshold and switching back to GNSS when it rises above. However, in scenarios such as urban canyons, under overpasses, in dense foliage, near large windows, and in semi-open venues, GNSS signals attenuate, even though the user is still in an outdoor or semi-outdoor environment. Judging solely by signal strength leads to frequent false switching and positioning jumps. Furthermore, when a user actually enters a building (e.g., through a lobby or elevator), there is a time lag between signal attenuation and changes in movement, making it difficult to accurately determine the user's "entry" or "exit" intentions based solely on signal thresholds.

[0004] Therefore, there is a need for an intelligent clothing positioning solution that can combine the user's movement state and intentions to improve the accuracy of indoor and outdoor switching. Summary of the Invention

[0005] The purpose of this invention is to provide a smart garment that enables indoor and outdoor positioning switching based on motion state driving. It utilizes an IMU worn close to the body to accurately sense the human body's motion state, uses the change of motion state as the main driving condition for indoor and outdoor positioning switching, combines GNSS signal quality for dual-condition confirmation, and suppresses erroneous switching through hysteresis threshold and transition period dead reckoning, thereby improving positioning continuity and accuracy.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A smart garment that achieves indoor and outdoor positioning switching based on motion state drive includes a garment body, on which a main control unit, an inertial measurement unit (IMU), a GNSS positioning module, an indoor positioning module, and a power module are provided; the IMU, GNSS positioning module, indoor positioning module, and power module are respectively connected to the main control unit;

[0008] The main control unit performs the following positioning method:

[0009] S1. Motion state recognition: The main control unit collects triaxial acceleration and triaxial angular velocity data from the IMU at a frequency of f1. Within a sliding time window of length W, it extracts the peak-to-peak value A_pp and step frequency f_step of the acceleration signal. Based on A_pp and f_step, the human motion state is classified into stationary, walking and running.

[0010] S2, Signal Quality Acquisition: The main control unit acquires the carrier-to-noise ratio C / N0 output by the GNSS positioning module at a frequency of f2;

[0011] S3. Outdoor to Indoor Switching Decision: When the system is in outdoor positioning mode, if the following conditions are met simultaneously and the first confirmation time T1 is maintained, then the system will switch to indoor positioning mode:

[0012] (a) C / N0 decreases below the entry threshold C_in;

[0013] (b) The state of motion changes from walking or running to rest, or the cadence f_step is lower than the lower limit of walking f_low;

[0014] S4. Indoor to Outdoor Switching Decision: When the system is in indoor positioning mode, if the following conditions are met simultaneously and continue for the second confirmation time T2, then the system will switch to outdoor positioning mode:

[0015] (a) The motion state changes from rest to walking or running, or the step frequency f_step is higher than the lower limit of walking f_low;

[0016] (b) C / N0 rises above the exit threshold C_out, and the exit threshold C_out is greater than the entry threshold C_in;

[0017] S5. Transition Connection: During the transition time ΔT before and after the positioning mode switch, the main control unit uses the IMU dead reckoning result as the positioning output to smoothly connect the positioning coordinates at the two times before and after the switch.

[0018] Furthermore, the specific method for classifying motion states in step S1 is as follows:

[0019] When A_pp < A0, it is considered stationary;

[0020] When A_pp ≥ A0 and f_step ∈ [f_low, f_high], it is determined to be walking;

[0021] When A_pp ≥ A0 and f_step > f_high, it is determined to be running;

[0022] Where A0 is the static acceleration threshold, f_low is the lower limit frequency for walking, and f_high is the lower limit frequency for running.

[0023] Furthermore, the step frequency f_step is obtained by performing autocorrelation analysis on the acceleration synthesis signal within the sliding window after removing the mean, and taking the reciprocal of the delay corresponding to the first significant peak of the autocorrelation function.

[0024] Furthermore, in steps S3 and S4, the entry threshold C_in is set to 25~30 dB-Hz, the exit threshold C_out is set to 35~40 dB-Hz, and a hysteresis interval is formed between C_out and C_in; the first confirmation time T1 is set to 3~8 seconds, the second confirmation time T2 is set to 5~15 seconds, and T2 > T1.

[0025] Furthermore, the method for IMU dead reckoning in step S5 is as follows:

[0026] Using the positioning coordinates and heading at the last moment before the switch as initial values, the velocity is obtained by integrating the acceleration output by the IMU after gravity component compensation, and the displacement increment is obtained by integrating again. The heading increment is obtained by integrating the angular velocity output by the gyroscope. The positioning coordinates are recursively calculated within the transition time period ΔT. After the new mode completes the first effective positioning output, the cumulative error of dead reckoning is corrected with the new mode coordinates and the transition state is exited.

[0027] Furthermore, the indoor positioning module is a UWB positioning module or a BLE beacon positioning module.

[0028] Furthermore, the garment body is also provided with flexible conductive yarn, and the main control unit is electrically connected to the IMU, GNSS positioning module, indoor positioning module and power module through the flexible conductive yarn; the flexible antenna of the GNSS positioning module is sewn to the shoulder position of the garment body, and the antenna of the indoor positioning module is sewn to the chest position of the garment body.

[0029] Furthermore, the main control unit, IMU, GNSS positioning module, indoor positioning module, and power module are all detachably connected to the garment body via conductive snaps.

[0030] Furthermore, the garment body is also equipped with a heart rate sensor and a body temperature sensor connected to the main control unit.

[0031] The present invention also provides an indoor-outdoor positioning switching method based on motion state driving, using the above-mentioned smart clothing, including the above-mentioned steps S1-S5.

[0032] The beneficial effects of this invention are as follows:

[0033] 1. Using the change in motion state as the main driving condition for indoor-outdoor switching. When users enter or exit a building, their motion state is usually accompanied by a change from "walking → stopping" (entering) or "stopping → walking" (exiting). This motion intention reflects the real indoor-outdoor scene switching better than simple signal attenuation, effectively avoiding false switching caused by temporary signal attenuation in scenes such as urban canyons, shady areas, and windowsills.

[0034] 2. A dual-condition confirmation mechanism of "motion state + signal quality" is adopted. Both conditions must be met simultaneously and for a certain period of time before the switch is triggered, which significantly reduces the probability of false triggering.

[0035] 3. The hysteresis interval is formed by the difference between the entry threshold C_in and the exit threshold C_out, and the entry confirmation time T1 is shorter than the exit confirmation time T2. This ensures that the positioning is not lost when entering the room, and avoids repeated jumping in boundary areas such as doorways and windows.

[0036] 4. During the transition period, IMU dead reckoning is used to fill the output gap between the old and new positioning modes, ensuring continuous positioning coordinates without jumps, thus improving the user experience.

[0037] 5. Each module is detachably connected to the garment body via conductive snaps, facilitating charging, cleaning, and maintenance; the GNSS antenna is positioned on the shoulder, and the indoor antenna is positioned on the chest, taking into account both the orientation of satellite signal reception and the propagation characteristics of ultra-wideband signals to the human body. Attached Figure Description

[0038] Figure 1 This is a structural schematic diagram of the smart clothing of the present invention;

[0039] Figure 2 This is a system principle block diagram of the present invention;

[0040] Figure 3 This is a flowchart of the indoor / outdoor positioning switching method based on motion state driving according to the present invention.

[0041] Reference numerals: 1. Garment body; 2. Main control unit; 3. IMU; 4. GNSS positioning module; 5. Indoor positioning module; 6. Power module; 9. Heart rate sensor; 10. Body temperature sensor; 41. GNSS flexible antenna; 51. Indoor positioning antenna. Detailed Implementation

[0042] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0043] Example 1

[0044] like Figure 1-3As shown, a smart garment that achieves indoor / outdoor positioning switching based on motion state drive includes a garment body 1. The garment body 1 is equipped with a main control unit 2, an inertial measurement unit (IMU) 3, a GNSS positioning module 4, an indoor positioning module 5, a power module 6, a heart rate sensor 9, and a body temperature sensor 10. The main control unit 2 includes an MCU and a memory. The IMU 3 is a six-axis device (three-axis accelerometer + three-axis gyroscope). The GNSS positioning module 4 supports GPS and BeiDou. The indoor positioning module 5 is a UWB positioning module (or a BLE beacon positioning module in other embodiments). The power module 6 is a rechargeable lithium battery.

[0045] Flexible conductive yarn is sewn onto the garment body 1. The main control unit 2 is electrically connected to the IMU 3, GNSS positioning module 4, indoor positioning module 5, power module 6, heart rate sensor 9, and body temperature sensor 10 via the flexible conductive yarn to achieve power supply and data communication. The GNSS flexible antenna 41 of the GNSS positioning module 4 is sewn onto the shoulder of the garment body 1, with the shoulder facing the sky to facilitate satellite signal reception. The indoor positioning antenna 51 (UWB antenna) of the indoor positioning module 5 is sewn onto the chest of the garment body 1. The main control unit 2, IMU 3, GNSS positioning module 4, indoor positioning module 5, power module 6, heart rate sensor 9, and body temperature sensor 10 are all detachably connected to the garment body 1 via conductive snaps, making it easy to remove for charging and washing. The IMU 3 is fixed to the chest or lower back of the garment body 1, remaining relatively stationary with respect to the torso to avoid interference from limb movement in motion recognition.

[0046] After powering on, the main control unit 2 defaults to outdoor positioning mode and executes the following steps:

[0047] S1. Motion state recognition:

[0048] Main control unit 2 acquires triaxial acceleration (a_x, a_y, a_z) and triaxial angular velocity (g_x, g_y, g_z) data from IMU3 at a frequency f1 = 50 Hz. The composite amplitude of the triaxial accelerations is then calculated.

[0049] a_mag = √(a_x² + a_y² + a_z²)

[0050] Within a sliding time window of length W = 2 seconds (i.e., 100 sampling points), calculate the peak-to-peak value of a_mag, A_pp = max(a_mag) − min(a_mag).

[0051] After removing the mean from a_mag within the window, perform autocorrelation analysis and take the time delay τ corresponding to the first significant peak of the autocorrelation function. The step frequency f_step = 1 / τ. For example, the step frequency during normal walking is about 1.5~2.5 Hz, and the step frequency during running is about 2.5~4 Hz.

[0052] Classify motion states according to the following rules:

[0053] When A_pp < A0 = 0.8 m / s², it is determined to be stationary;

[0054] When A_pp ≥ 0.8 m / s² and f_step ∈ [f_low=1.2 Hz, f_high=2.5 Hz], it is determined to be walking;

[0055] When A_pp ≥ 0.8 m / s² and f_step > 2.5 Hz, it is determined to be running.

[0056] The sliding window slides once per second, and the motion state recognition results are updated once per second.

[0057] S2, Signal Quality Acquisition:

[0058] The main control unit 2 collects the carrier-to-noise ratio C / N0 (unit dB-Hz) output by the GNSS positioning module 4 at a frequency of f2=1 Hz, and takes the average C / N0 of the four strongest satellites currently being tracked as the signal quality index.

[0059] S3, Outdoor to Indoor Transition Judgment:

[0060] When the system is in outdoor positioning mode, it continuously monitors the above two conditions:

[0061] (a) C / N0 decreases to below the entry threshold C_in = 28 dB-Hz;

[0062] (b) The movement state changes from walking or running to standing still, or the step frequency f_step is lower than the walking lower limit f_low=1.2Hz (indicating that the user has stopped and may have entered the room to sit or stand).

[0063] If both conditions are met simultaneously and the first confirmation time T1=5 seconds are maintained, it is determined that the user has entered the indoor environment. The main control unit 2 shuts down the GNSS positioning module 4 (or puts it into a low-power standby state), starts the indoor positioning module 5, and switches to indoor positioning mode.

[0064] If only signal attenuation is satisfied but motion state transition is not satisfied (e.g., a user is walking in the shade of a tree outdoors but C / N0 temporarily decreases), a handover will not be triggered to avoid misjudgment.

[0065] S4. Indoor to Outdoor Determination:

[0066] When the system is in indoor positioning mode, it continuously monitors:

[0067] (a) The motion state changes from stationary to walking or running, or the step frequency f_step is higher than f_low=1.2 Hz (indicating that the user has started walking and may be leaving the building).

[0068] (b) C / N0 rises above the exit threshold C_out = 38 dB-Hz.

[0069] If both conditions are met simultaneously and the second confirmation time T2 = 10 seconds is maintained, it is determined that the user has left the indoor area. The main control unit 2 shuts down the indoor positioning module 5, restarts the GNSS positioning module 4, and switches to the outdoor positioning mode.

[0070] The exit threshold C_out = 38 dB-Hz is greater than the entry threshold C_in = 28 dB-Hz, forming a hysteresis interval of 10 dB-Hz between them, and T2 = 10 seconds > T1 = 5 seconds. The reason for this design is that when entering indoors, the signal attenuates faster and the movement stops more clearly, allowing for quick switching; while when leaving indoors, the GNSS signal may briefly recover in areas such as doorways and windows, but the user has not actually completely left, requiring a longer confirmation time and a higher signal threshold to prevent repeated hopping.

[0071] S5. Transition and Connection:

[0072] During the transition period ΔT (2-3 seconds) before and after the positioning mode switch, the new mode is still unstable at startup (for example, it takes several seconds for GNSS to reacquire satellites, or for UWB to enter a new cell and require base station ranging). The main control unit 2 uses the IMU dead reckoning result as the positioning output:

[0073] Using the positioning coordinates (x0, y0) and heading θ0 at the last moment before the switch as initial values, the acceleration output by IMU 3 is compensated for by gravity components (by using gyroscope attitude estimation to convert the body coordinate system acceleration to the navigation coordinate system). Then, the velocity v(t) = v0 + ∫a(t)dt is obtained by integration, and the displacement increments Δx = ∫v_x(t)dt and Δy = ∫v_y(t)dt are obtained by further integration. The heading is obtained by integrating the gyroscope angular velocity θ(t) = θ0 + ∫ω(t)dt. The positioning coordinates (x0 + Δx, y0 + Δy) are recursively derived within ΔT.

[0074] Once the new mode completes its first effective positioning output (GNSS obtains a 3D fixed solution, or UWB completes TDOA calculations for at least 3 base stations), the accumulated error in dead reckoning is corrected using the new mode coordinates as a reference. Then, it exits the transition state and enters normal positioning output. During the transition period, the positioning coordinates change continuously without any jumps from indoor to outdoor coordinates.

[0075] The human physiological data collected by the heart rate sensor 9 and the body temperature sensor 10 are packaged together with the positioning data through the main control unit 2 and uploaded to the user's mobile phone or monitoring platform via the Bluetooth module (integrated in the main control unit 2).

[0076] Example 2

[0077] The difference between this embodiment and Embodiment 1 is that the indoor positioning module 5 uses a BLE beacon positioning module, which performs RSSI ranging and positioning by receiving the signal strength of BLE beacons deployed indoors. It is suitable for places such as shopping malls and hospitals where BLE beacons have already been deployed. The rest of the structure and method are the same as in Embodiment 1.

[0078] Example 3

[0079] This embodiment provides an indoor / outdoor positioning switching method based on motion state driving, using the smart clothing described in Embodiment 1, and executing steps S1-S5, which will not be repeated here.

[0080] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A smart garment that achieves indoor / outdoor positioning switching based on motion state driving, comprising a garment body (1), characterized in that: The garment body (1) is equipped with a main control unit (2), an inertial measurement unit (IMU) (3), a GNSS positioning module (4), an indoor positioning module (5) and a power module (6), and the IMU (3), GNSS positioning module (4), indoor positioning module (5) and power module (6) are respectively connected to the main control unit (2); The main control unit (2) is configured as follows: Acceleration and angular velocity data of IMU (3) are collected at frequency f1. The peak-to-peak value of acceleration A_pp and the step frequency f_step are extracted within a sliding time window of length W, and the motion state is classified into stationary, walking and running. The carrier-to-noise ratio C / N0 of the GNSS positioning module (4) is collected at frequency f2; When in outdoor positioning mode, if C / N0 is lower than the entry threshold C_in, and the movement state changes from walking or running to standing still or the step frequency f_step is lower than the walking lower limit f_low, and this state lasts for the first confirmation time T1, then switch to indoor positioning mode. When in indoor positioning mode, if the motion state changes from stationary to walking or running or the step frequency f_step is higher than the walking lower limit f_low, and C / N0 is higher than the exit threshold C_out, and this state lasts for the second confirmation time T2, then switch to outdoor positioning mode, where C_out > C_in; During the transition period ΔT before and after the positioning mode switch, the IMU dead reckoning result is used as the positioning output for a smooth transition.

2. The smart clothing according to claim 1, characterized in that: The main control unit (2) classifies motion states according to the following rules: when A_pp < A0, it is determined to be stationary; when A_pp ≥ A0 and f_low ≤ f_step ≤ f_high, it is determined to be walking; when A_pp ≥ A0 and f_step > f_high, it is determined to be running; where A0 is the static acceleration threshold, f_low is the lower limit frequency of walking, and f_high is the lower limit frequency of running.

3. The smart clothing according to claim 2, characterized in that: The step frequency f_step is obtained by performing autocorrelation analysis on the triaxial acceleration synthesized signal within the sliding window after removing the mean, and taking the reciprocal of the delay corresponding to the first significant peak of the autocorrelation function.

4. The smart clothing according to claim 1, characterized in that: The entry threshold C_in is 25~30 dB-Hz, and the exit threshold C_out is 35~40 dB-Hz; the first confirmation time T1 is 3~8 seconds, the second confirmation time T2 is 5~15 seconds, and T2 > T1.

5. The smart clothing according to claim 1, characterized in that: The IMU dead reckoning uses the positioning coordinates and heading at the last moment before the switch as the initial values. It uses the IMU acceleration integral after gravity component compensation to obtain the velocity and displacement increments, and uses the gyroscope angular velocity integral to obtain the heading increments. The positioning coordinates are recursively calculated during the transition time period ΔT. After the new mode completes the first effective positioning output, the cumulative error of the dead reckoning is corrected with the new mode coordinates.

6. The smart clothing according to claim 1, characterized in that: The indoor positioning module (5) is a UWB positioning module or a BLE beacon positioning module.

7. The smart clothing according to claim 1, characterized in that: Flexible conductive yarn is sewn onto the garment body (1). The main control unit (2) is electrically connected to the IMU (3), GNSS positioning module (4), indoor positioning module (5) and power module (6) through the flexible conductive yarn. The GNSS flexible antenna (41) of the GNSS positioning module (4) is sewn onto the shoulder of the garment body (1), and the indoor positioning antenna (51) of the indoor positioning module (5) is sewn onto the chest of the garment body (1).

8. The smart clothing according to claim 7, characterized in that: The main control unit (2), IMU (3), GNSS positioning module (4), indoor positioning module (5) and power module (6) are all detachably connected to the garment body (1) via conductive snaps.

9. The smart clothing according to claim 1, characterized in that: The garment body (1) is also equipped with a heart rate sensor (9) and a body temperature sensor (10) connected to the main control unit (2).

10. A method for switching between indoor and outdoor positioning based on motion state, characterized in that, The smart clothing described in any one of claims 1-9 includes the following steps: S1. Acquire acceleration and angular velocity data of the IMU at frequency f1, extract the peak-to-peak acceleration A_pp and step frequency f_step within the sliding time window W, and classify the motion state into stationary, walking and running. S2. Collect the GNSS carrier-to-noise ratio C / N0 at frequency f2; S3. When in outdoor positioning mode, if C / N0 is lower than C_in and the movement state changes from walking or running to standing still or the step frequency is lower than f_low and continues for T1, switch to indoor positioning mode. S4. When in indoor positioning mode, if the movement state changes from stationary to walking or running or the step frequency is higher than f_low and C / N0 is higher than C_out and continues for T2, switch to outdoor positioning mode, C_out > C_in; S5. During the transition period ΔT before and after the switch, the positioning output is smoothly connected using the IMU dead reckoning results.

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